High-sensitivity sensor system, detection circuit, and detection method

Abstract

It is an object of the present invention to reduce noise in a detection circuit for use in a sensor system. According to an aspect of the present invention, provided is a high-sensitivity sensor system which includes an acceleration sensor, a detection circuit system that detects an output of the acceleration sensor, a feedback circuit system including a reference voltage power source that generates a feedback signal to be fed back to the acceleration sensor based on an output of the detection circuit system, and a correction circuit system. The correction circuit system includes a reference power source variation detection circuit that detects a variation component from a reference voltage of the reference voltage power source, an output signal error calculation circuit that receives an output of the reference power source variation detection circuit as an input, and calculates a change in the variation component up to the output of detection circuit system via the acceleration sensor, and an operation circuit that subtracts an output of the output signal error calculation circuit from the output of the detection circuit system.

The invention claimed is: 
     
       1. A high-sensitivity sensor system, comprising:
 an acceleration sensor; 
 a detection circuit that detects an output of the acceleration sensor; 
 a feedback circuit including a reference voltage power source that generates a feedback signal to be fed back to the acceleration sensor based on an output of the detection circuit system; and 
 a correction circuit comprising
 a reference power source variation detection circuit that detects a voltage variation component with respect to a reference voltage of the reference voltage power source, 
 an output signal error calculation circuit that receives an output of the reference power source variation detection circuit as an input, and calculates a change in the voltage variation component up to the output of detection circuit via the acceleration sensor, and 
 an operation circuit that subtracts an output of the output signal error calculation circuit from the output of the detection circuit. 
 
 
     
     
       2. The high-sensitivity sensor system according to  claim 1 ,
 wherein the detection circuit comprises: 
 a signal detection circuit that converts an output of a micro electro mechanical systems (MEMS) serving as an acceleration sensor into a voltage signal, 
 a noise shaping filter that receives the output of the signal detection circuit as an input, 
 a phase corrector that corrects a phase of an output of the noise shaping filter, and 
 a quantization circuit that quantizes an output of the phase corrector. 
 
     
     
       3. The high-sensitivity sensor system according to  claim 1 ,
 wherein the feedback circuit comprises: 
 a digital-to-analog (D/A) converter that receives the reference voltage from the reference voltage power source as an input, and 
 a conversion circuit that uses an output of the D/A converter as an input to the acceleration sensor. 
 
     
     
       4. The high-sensitivity sensor system according to  claim 1 ,
 wherein the correction circuit comprises: 
 as the reference power source variation detection circuit, 
 a capacitive element that receives an output of the reference voltage power source as an input, 
 a modulator that receives an output of the capacitive element as an input, 
 a band pass filter that receives an output of the modulator as an input, 
 an analog-to-digital (A/D) converter that receives an output of the band pass filter as an input, 
 a demodulator that receives an output of the A/D converter as an input, and 
 a low pass filter that receives an output of the demodulator as an input. 
 
     
     
       5. The high-sensitivity sensor system according to  claim 1 , further comprising,
 an output side low pass filter that extracts a frequency band of 1 kHz or less from the output of the detection circuit. 
 
     
     
       6. A high-sensitivity detection circuit, comprising:
 a detection circuit that detects a signal output from an acceleration sensor; 
 a feedback circuit including a reference voltage power source that generates a feedback signal to be fed back to the acceleration sensor based on an output of the detection circuit; and 
 a correction circuit comprising
 a reference power source variation detection circuit that detects a voltage variation component with respect to a reference voltage of the reference voltage power source, 
 an output signal error calculation circuit that receives an output of the reference power source variation detection circuit as an input, and calculates a change in the voltage variation component up to the output of detection circuit via the acceleration sensor, and 
 an operation circuit that subtracts an output of the output signal error calculation circuit from the output of the detection circuit. 
 
 
     
     
       7. The high-sensitivity detection circuit according to  claim 6 ,
 wherein the detection circuit includes 
 a signal detection circuit that converts an output of a micro electro mechanical systems (MEMS) serving as an acceleration sensor into a voltage signal, 
 a noise shaping filter that receives the output of the signal detection circuit as an input, 
 a phase corrector that corrects a phase of an output of the noise shaping filter, and 
 a quantization circuit that quantizes an output of the phase corrector. 
 
     
     
       8. The high-sensitivity detection circuit according to  claim 6 ,
 wherein the feedback circuit comprises: 
 a digital-to-analog (D/A) converter that receives the reference voltage from the reference voltage power source as an input, and 
 a conversion circuit that uses an output of the D/A converter as an input to the acceleration sensor. 
 
     
     
       9. The high-sensitivity detection circuit according to  claim 6 ,
 wherein the correction circuit comprises: 
 as the reference power source variation detection circuit, 
 a capacitive element that receives an output of the reference voltage power source as an input, 
 a modulator that receives an output of the capacitive element as an input, 
 a band pass filter that receives an output of the modulator as an input, 
 an analog-to-digital (A/D) converter that receives an output of the band pass filter as an input, 
 a demodulator that receives an output of the A/D converter as an input, and 
 a low pass filter that receives an output of the demodulator as an input. 
 
     
     
       10. The high-sensitivity detection circuit according to  claim 6 , further comprising,
 an output side low pass filter that extracts a frequency band of 1 kHz or less from the output of the detection circuit. 
 
     
     
       11. A high-sensitivity detection method, comprising:
 electrically detecting an output of an acceleration sensor; 
 generating a feedback signal to be fed back to the acceleration sensor based on a detection signal detected in the electrically detecting step, using a reference voltage; and 
 performing a correction process including 
 using a reference power source variation detection process, detecting a voltage variation component with respect to the reference voltage, 
 performing an output signal error calculation process of calculating a change which the voltage variation component applies to the detection signal, and 
 subtracting the change from the detection signal detected in the detection process. 
 
     
     
       12. The high-sensitivity detection method according to  claim 11 ,
 wherein the electrically detecting further comprises: 
 using a signal detection circuit, converting an output of a micro electro mechanical systems (MEMS) serving as an acceleration sensor into a voltage signal, 
 receiving an output of the signal detection circuit by a noise shaping filter, 
 correcting a phase of an output of the noise shaping filter, and 
 quantizing an output of the phase corrector are used. 
 
     
     
       13. The high-sensitivity detection method according to  claim 11 ,
 wherein said step of generating a feedback signal comprises: 
 receiving the reference voltage at a digital-to-analog (D/A) converter, and 
 receiving an output of the D/A converter as an input to the acceleration sensor via a conversion circuit. 
 
     
     
       14. The high-sensitivity detection method according to  claim 11 ,
 wherein the correction process; comprises: 
 receiving the reference voltage by a capacitive element, 
 receiving an output of the capacitive element by a modulator, 
 receiving an output of the modulator by a band pass filter, 
 receiving an output of the band pass filter by an analog-to-digital (A/D) converter, 
 receiving an output of the A/D converter by a demodulator, and 
 receiving an output of the demodulator by a low pass filter. 
 
     
     
       15. The high-sensitivity detection method according to  claim 11 ,
 extracting a frequency band of 1 kHz or less from the output of the electrically detecting using an output side low pass filter. 
 
     
     
       16. The high-sensitivity detection method according to  claim 11 , further comprising:
 performing underground resource exploration using a plurality of said high-sensitivity sensor systems, 
 wherein each said high-Sensitivity, sensor system comprises 
 an acceleration sensor; 
 a detection circuit that detects an output of the acceleration sensor; 
 a feedback circuit including a reference voltage power source that generates a feedback signal to be fed back to the acceleration sensor based on an output of the detection circuit system; and 
 a correction circuit comprising
 a reference power source variation detection circuit that detects a voltage variation component with respect to a reference voltage of the reference voltage power source, 
 an output signal error calculation circuit that receives an output of the reference power source variation detection circuit as an input, and calculates a change in the voltage variation component up to the output of detection circuit via the acceleration sensor, and 
 
 an operation circuit that subtracts an output of the output signal error calculation circuit from the output of the detection circuit.